1. Field of the Invention
The present invention relates generally to paint systems for vehicles and, more specifically, to an integrated paint quality control system for feedback control of paint process for painting bodies of vehicles.
2. Description of the Related Art
The application of paint to a body of a vehicle is a sensitive process. The quality, durability and color matching of the paint are critical in producing a high quality product, and therefore require significant quality control efforts. A paint booth is used to apply the paint to the vehicle bodies. The thickness of the film build measured from the vehicle body and quality measurement system (QMS) quality characteristics (gloss, distinctiveness of image, orange peel, and their aggregated value) are the outputs of the paint process. However, the film thickness and the QMS quality characteristics of the paint may vary with location due to geometric differences of the vehicle body. These output characteristics also vary from vehicle body to vehicle body because of process variability.
Although most of the process parameters (bell speed, paint flows, humidity, booth air flows) are controlled by feedback control systems, the paint process as a system is not automatically controlled. As a result, it is desirable to provide an automatic integrated paint quality control system that monitors and supervisory controls the paint process in terms of paint quality characteristicsxe2x80x94film thickness and QMS. It is also desirable to provide an integrated paint quality control system that minimizes the number of vehicles that lack paint thickness uniformity in painting of vehicle bodies. It is further desirable to provide an integrated paint quality control system that allows for quick identification of paint variability and immediately responds with proper adjustment of settings for a paint booth for painting vehicle bodies.
Accordingly, the present invention is an integrated paint quality control (IPQC) system for feedback control of paint process for painting vehicle bodies including a film thickness sensor system for measuring paint film thickness of the painted bodies. The IPQC system also includes a control system communicating with the film thickness sensor system for receiving information of the paint film thickness and combining the paint film thickness information with paint automation parameters on a vehicle identification number (VIN) basis of the painted bodies to control the paint process.
One advantage of the present invention is that an integrated paint quality control system is provided for feedback control of a paint process for painting vehicle bodies. Another advantage of the present invention is that the integrated paint quality control system does not eliminate or change existing feedback control systems that control most of the paint process parameters. Yet another advantage of the present invention is that the integrated paint quality control system functions as a supervisory control system that updates their set points based on the output process parametersxe2x80x94film thickness and QMS characteristics. Still another advantage of the present invention is that the integrated paint quality control system monitors and supervisory controls the paint process in terms of paint uniformity. A further advantage of the present invention is that the integrated paint quality control system allows for quick identification of paint variability due to changes in paint booth environment, paint equipment, and paint characteristics and immediately responds for proper adjustment of automation equipment settings. Yet a further advantage of the present invention is that the integrated paint quality control system is capable of identifying on-line paint thickness variability immediately after a vehicle has been painted. Still a further advantage of the present invention is that the integrated paint quality control system automatically analyzes the cause for the variation and calculates paint process parameter settings of local paint automation equipment that can compensate for this variation. Another advantage of the present invention is that the integrated paint quality control system minimizes the number of vehicles that lack paint thickness uniformity. Yet another advantage of the present invention is that the integrated paint quality control system keeps track of the paint process parameters that are out of specification and identifies equipment failures. Still another advantage of the present invention is that the integrated paint quality control system summarizes all paint process data and links to a vehicle identification number of the vehicle bodies, which provides for process/quality data mining and optimization in a later stage.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.